Output shaft coupling mechanism for multiple power plants



y 1950 c. c. DE PEW arm. 2,505,853

OUTPUT SHAFT COUPLING IIECHANISII, FOR MULTIPLE POWER PLANTS OriginalFiled Jan. 28, 1944 3 Sheets-Sheet 1 INVENTOR3 menu-a ,zntaakr aware ,0.as"

May 2, 1950 c. c. DE PEW ETAL 2,505,353 OUTPUT SHAFT couruus uEcl-mmsuFOR IIULTIPLE POWER PLANTS Original Filed Jan. '28, 1944 s Sheets-Sheet2.

A4 FRED 7: 60mm? ewes re! a ens 2,505,853 MECHANISM PLANTS 3Sheets-Sheet 3 \NVENTORS ALMA-D ZGREGORY May2, 1950 c. DE PEW ETALOUTPUT FT COUPLING FOR MULTIPLE POWER Original Filed Jan. 28, 1944Patented May 2, 1950 OUTPUT SHAFT OOUPLIN G MECHANISM F OR MULTIPLEPOWER PLANTS Chester 0. De Pew, Farmingdale, and Alfred '1.

Gregory, Massapequa, N. Y., assignors to Fairchild Engine and AirplaneCorporation, Farmingdale, N. Y., a corporation of Maryland Continuationof application Serial No. 520,040, January 28, 1944. This applicationDecember 29, 1948, Serial No. 67,958

6 Claims. (Cl. 74-4565) This invention relates to internal combustionengines, and has particular reference to engines having two crankshaftsfor driving one or more aircraft propellers, although the invention isnot limited to aeronautical use. This application is a continuation ofcopending application Serial No. 520,040, filed January 28, 1944, nowforfeited.

Multiple crankshaft aeronautical engines have been devised heretoforeinvolving the use of two crankshafts for driving coaxialcounter-rotating propellers, each propeller being independently drivenby a corresponding crankshaft so that in effect two engines are in use,or both crankshafts drive a common shaft connected to one propeller withthe other propeller being driven in the opposite direction from thecommon shaft through reversing gearing. In the case of the independentlydriven propellers, the corresponding crankshafts are severally operatedby corre-' sponding complete engines or by separate banks of cylindersseverally connected to the corresponding crankshafts and operating ineffect as separate engines. It is desirable to have both crankshaftsconnected to the propeller shaft or shafts, so that failure of onecrankshaft driving mechanism will not disable the propeller drive exceptto reduce its power. Also, it is desirable to place one crankshaft outof operation at will under conditions of lower power requirements, aswhen cruising, which suggests the use of a clutch, but the mereinterposition of a clutch does not suffice because the clutch createsthe problem of securing necessary synchronization between the twocrankshafts when it becomes necessary to reclutch the inactivecrankshaft unit to the propeller shaft or shafts. The provision of aselfsynchronizing clutch mechanism which enables clutching anddeclutching of the two crankshaft units while automatically attainingand maintaining synchronism between them is accordingly necessary tosolve the problem, and the present invention is primarily directed tothe provision of a multiple crankshaft engine embodying saidself-synchronizing clutch mechanism.

In accordance with the present invention, a multiple crankshaftaeronautical engine is provided in which two crankshafts severallydriven by separate banks of cylinders are directly geared together andto the propeller shaft or shafts. Interposed between one of thecrankshafts and the connected gearing is a self-synchronizing clutchmechanism whereby one crankshaft unit may be connected to ordisconnected from the other crankshaft unit and the propeller shaft atwill, so that both crankshafts operate together in synchronism, or onecrankshaft operates alone and without disconnecting the propellershafting.

By means of the organization of gearing and synchronizing clutchmechanism described, one of the two crankshaft units, comprisingcylinders and its crankshaft, is set'intooperation when starting theengine and after it has attained a predetermined rate of rotation it isemployed to start the other crankshaft unit by means of theself-synchronizing clutch mechanism which is engaged to connect thesecond, theretofore inactive, crankshaft into operation under suchconditions that the second crankshaft does not cooperate in the drivingoperation until it has achieved synchronism with the first or startingcrankshaft and then it is automatically coupled thereto. Aftersynchronism between the two crankshafts has thus been automaticallyachieved, it is maintained during the entire operating period of theengine.

Preferably, the bank of cylinders driving each crankshaft comprises tworows of cylinders arranged substantially in a common vertical plane buton the same crankcase so that the engine is an H-type engine, althoughthe cylinders for each crankshaft may be arranged otherwise, dependingon requirements, and thus may form a star engine, opposed cylinderpancake engine, or other form involving the use of two crankshafts.

It will be seen that the internal combustion engine of this inventionprovides many advantages, including the increased power obtainable withthe multiple crankshaft arrangement, but without involving thecomplications accompanying the use of such engines, but on the contrary,

it has practically the simplicity, lightness, and operating advantagesof a single crankshaft engine having an equal number of cylinders. Aswill be observed, one of the crankshaft-cylinder components may beoperated alone without disturbing the aeronautical balance of the craftand without undue stresses occasioned by the connection or disconnectionof the second crankshaft to and from the propeller mechanism.

For a more complete understanding of the invention, reference may be hadto the accompanying drawings, in which: V

Figure l is a propeller end view of the internal combustion engine ofthis invention;

Fig. 2 is a horizontal enlarged section through the propeller drivingmechanism of the engineof Fig. 1, as seen along the line 2-2 of Fig. 1;

Fig. 3 is an enlarged axial section through the driving pinion on one ofthe crankshafts as seen along the line 3-3 of Fig. 2, and illustratesthe synchronizing clutching mechanism for placing the correspondingcrankshaft into and out of driving operation; and

Fig. 4 is a section through the synchronizing ratchet as seen along line4-4 of Fig. 3.,

Referring to Fig. 1 of the drawings, numeral ll designates anaeronautical engine having two crankshafts whose centers are located atH and I2, each of which is operated by two rows of cylinders arrangedsubstantially in the vertical plane of the corresponding crankshaft,although they are inclined with respect to the vertical of plane asshown for purposes of accessibility of the auxiliaries and other partslocated between the two rows of cylinders at the top and the bottom ofthe engine. The outline of engine In is shown in silhouette by dottedlines in Fig. 1, since the particular construction of the cylinders andcombustion chambers of the engine form no part of the present invention.Thus, the upper row of cylinders designated l3 and the lower row ofcylinders designated i3 at the right hand side of the engine operate acrankshaft whose center is located at Ii while the upper row ofcylinders l4 and the lower row of cylinders l4 at the other or left handside of the engine operate the crankshaft whose center is located at l2.The crankshafts are driven in the same direction of rotation. I

. Each row of cylinders, l3, l3, l4, l4, may comprise six cylinders, forexample, so that the entire engine organization comprises twentyfourcylinders, the rows i3 and I3 constituting two cylinder banks for onecrankshaft and the rows i4 and i4 constituting two cylinder banks forthe other crankshaft, so that each crankshaft with its cylinder bankscomprise in fact a twelve cylinder wide V-type engine unit in theexample given. and each unit is provided with fuel supply, ignition andother systems required for operation, so that when both units are inoperation in synchronism, the engine constitutes a unitary power plantwhich may be enclosed within s uitable cowling, such as that designatedIS in Fig. 1. @However, when only one unit is operating the other unitis entirely inactive, and its fuel supply, including the air inductionsystem, the ignition, and the like, are all shut oflf;

Referring to Fig. 2, the crankshaft whose center of rotation is locatedat H is designated l8, and the crankshaft whose center of rotation islocated at i2 is designated [1. Only the pro peller ends of the twocrankshafts are shown in Fig. 2, since as before mentioned, theremainder of the engine, including details of cylinder, piston and othercrankshaft construction form no part of the present invention.Accordingly, it is sufficient to illustrate the propeller end of eachcrankshaft which is journalled in bearings I! mounted on the housing l9projecting forwardly from the engine as an extension of the crankcase,this housing bearing the relation to the engine that is indicated inFig. 2 by the position of the crank-pins l6 and ll of the frontcylinders of the corresponding banks.

Connected by a spline 20 to the propeller end of crankshaft I6 is aquill shaft 2i carrying the spur pinion 22, which is designated by thesame numeral in Fig. 1. The hub of the spur pinion 22 is suitablyjournalled in bearings 23 mounted in the housing I9. Similarly, thepropeller end of crankshaft I1 is fitted with the spur pinion 24, whichis designated by the same numeral in bly iournalled in bearings 2imounted in the housing ll.

Both spur pinions 22 and 24 on crankshafts II and I1, respectively, meshwith gear 28 journalled on a suitable bearing 21 on the propeller shaft28 which in turn is journalled in bearings 29 and 22 in housing I! asshown particularly in Fig. 2.

Gear 26 has the same diameter as crankshaft spur pinions 22 and 24 withwhich it meshes, so that a one-to-one driving ratio is provided. Thegear relation is illustrated in Fig. 1, where gear 24 is designated bythe same numeral.

*The quill 2| of gear 28 is journalled at its forward end on bearing 32and is provided with the sun gear 22 of a planetary reduction gearingconnecting gear with propeller shaft 28 for driving the latter at theproper speed. The planet pinions 24, also shown in Fig. 1, are carriedby spider 35 formed integrally with propeller shaft 28. These pinions 34mesh with sun gear 33 and also with stationary ring gear 28 secured tothe housing ll. As gear 24 is driven, its sun gear 23 causes planetpinions." to roll around stationary ring gear 24 to thereby rotatepropeller shaft 28 through spider II at the predetermined reductionratio. This gearing provides a direct speed reducing drive to thepropeller shaft 28 and the corresponding front propeller.

Positioned within pinion 24 of crankshaft i1 is a self-synchronizingclutching mechanism whereby crankshaft i1 may be connected to ordisconnected from crankshaft it at will. However, disconnection ofcrankshaft i! does not stop or otherwise affect the rotation ofpropeller shaft 28, because of its direct connection with operatingcrankshaft It. The self-synchronizing clutching mechanism which enablesone crankshaft to operate without affecting the operation of thepropeller in the'manner described is illustrated in enlarged axialsection in Fig. 3. The quill 21 of crankshaft i1 is fitted with axialsplines 38 upon which are slidable axially but not circumferentially thespaced friction discs 38, which may be eight in number, as shown. Theinterior of driving pinion 24 is also fitted with axial splines 4| onwhich are slidable axially but not circumferentially the eightcomplementary friction discs 4| which fit between the discs 39 connectedto the crankshaft quill 21.

Also mounted on internal spline 40 in pinion 24 so as to rotatetherewith in bearing 25 is an axially fixed retaining plate 42 held inplace by snap ring 43. Engaging the other end of the interleavedfriction discs 39 and 4| is a presser plate which is slidable axiallywithin the annular space formed between the interior of pinion 24 andthe exterior of quill 31 and containing the annular piston 45 engagingpresser plate 44. The back of piston 45 is hollow and forms pressurechamber 46 with the flange of the gear 24. When chamber 46 is suppliedwith pressure fluid, such as oil under pressure, piston 45 is caused tomove to the left, as seen in Fig. 3, to force presser plate 44 againstthe stack of friction discs 39, 4| to cause mioii 24 to be clutched toquill 31 and in turn to crankshaft I1, and vice versa.

The free end 31 of the quill 31 extends into the hub 24' of the pinion24 which is journalled within the bearing 25, and this free end 21' isprovided with a diametral slot 41, also shown in the sectionconstituting Fig. 4. Slidably mounted in this slot 41 for radialmovement is a synchronizing dog 4! whose outer end slidingly engages theeccentric or spiral inner surface 49 of Fig. 1. The hub of spur pinion24 is also suita- 7 hub 24' of gear 24. The ends of eccentric or spiralsurface 49 cooperate to form the abutment ll against which the free endof dog 40 is adapted to abut, as shown in Fig. 4, this arrangementconstituting a one-way clutch or ratchet construction between quill 21of crankshaft I1 and its pinion 24. v

The inner end of dog 48 is provided with a V-shaped slot or groove 5| soas to position its center of gravity near its outer end, the thin sidewalls of the slot 5| forming guides for the dog 48 in slot 41. The space52 between hub 24' and the free end 31' of quill 31 is supplied with oilunder pressure through a radial passage 52 in hub 24' communicating withan annular groove 54 in the bearing 25. This annular groove 54 isconnected by pipe 55 with a two-way valve 56 having one end of itscurved passage 51 connectible to pressure oil supply pipe 58 leadingfrom an oil pump or the like, and the other end of passage 51connectible to discharge pipe 5!. When the handle 60 is moved to theon-position shown in Fig. 3, oil flows from supply pipe 52 through valvepassage 51, pipe 55, annular groove 54, passage 53 and space 52 intochamber 45 to cause piston 45 to force presser plate 44 into engagementwith the friction discs 39 and 4|, which, being forced together betweenpresser plate 44 and axially-fixed back plate 42, causes pinion 24 to beclutched to quill 31 of crankshaft I1, and vice versa. When valve handle60 is moved to the off-position, the passage 51 in valve 56 connectspipe 55 to discharge pipe 59, so that the pressure on the friction discs39 and 4| is relieved, causing the clutch to disengage and pinion 24 tobe disconnected from quill 31 of crankshaft l1, and vice versa.

In operation of the engine illustrated in Figs. 1 and 2, when equippedwith the self-synchronizing clutch mechanism illustrated in Figs. 3 and4, the engine may be started by means of a conventional inertia or otherstarter connected to crankshaft IS with pinion 24 disconnected fromquill 31 of crankshaft l1 by reason of disengagement of the clutch shownin Fig. 3, the valve 55 being in the off-position. Accordingly, theright hand engine cylinder bank l3, 13' of Fig. 1 is started intooperation to drive corresponding crankshaft l6 independently ofcrankshaft l1. It will be observed that propeller shaft 28 is drivennotwithstanding the fact that crankshaft I1 is not in driving operation.The connection to propeller shaft 28 from operating crankshaft I6 isthrough gear train 22, 26, 33 and 34 to spider 35 on propeller shaft 28.

If the pilot or other operator desires to place the entire engine infull operation at once, he starts the other crankshaft unit, comprisingcylinder banks l4 and i4 and crankshaft 11, when crankshaft I6 hasachieved a, predetermined rotational speed which may be approximately2000 revolutions per minute, for example. This is accomplished by meansof valve 56, which is moved by the operator to the on-position to supplyoil under pressure from supply pipe 58 to pipe 55 whence it flowsthrough annular groove 54, passage 53, and space 52 to chamber 46, so asto cause piston 45 to force presser plate 44 to compress the frictiondiscs 39, 4| and thus connect pinion W to the quill 31 of crankshaft IT.This coupling of pinion 24 to crankshaft I1 causes crankshaft IIB torotate crankshaft 11 through gears 22, 2t and 24.

When crankshaft i1 is being rotated by crankshaft it at theaforementioned predetermined speed, say 2000 revolutions per minute. theopen- 6 ator closes the ignition switch for cylinder bank l4, H to causethe latter to drive crankshaft l1 simultaneously with operatingcrankshaft l5. Power then tends to flow from crankshaft 11 through theclutch shown in Fig. 3. When the power from crankshaft I1 is increasedsufficiently, the torque produced by the shaft will exceed that requiredto produce slippage of the slip clutch. The rotational speed of pinion24 will exert centrifugal force on dog 48, causing it to be forcedagainst eccentric or spiral surface 4!, creating a pressure dragthereon. As the torque of crankshaft I1 increases, it tends to overtakecrankshaft it until dog 48 engages abutment or detent 5| whensynchronism between the crankshafts is attained. The quill 31 ofcrankshaft I 1 and pinion 24 are directly and positively connectedtogether at the time that crankshaft I1 is in synchronism withcrankshaft l6.

Upon engagement of dog 48 with abutment or deient 50, power istransmitted from both crankshafts l6 and I1 through the connectinggearing to the propeller shaft 28 and the engine operates as a completeunit with both crankshafts synchronized. synchronism is maintained byreason of the direct gear interconnection of both crankshafts l6 and II.If it is desired to disconnect crankshaft l1 from the remainder of theengine during flight in order to improve fuel economy, for example, sothat the propeller isdriven by only engine cylinder banks l3, l3, andcrankshaft I6, the operator moves handle 59 to offposition to disconnectpinion 24 from quill 31 of crankshaft I1 and he also disconnects theignition for engine cylinder banks l4, l4, and closes the throttles inthe induction system to that side of the engine. Thereupon' the engineoperates as before but on approximately half power output provided byengine cylinder banks i3, I 2'.

When crankshaft I1 is thus rendered inoperative, it slows down, andabutment 50 moves away from dog 48, which is then moved radiallyinwardly by the spiral surface 49, against the opposition of centrifugalforce. Thereafter pinion 24 continues to rotate around stationary quillextension 31', since the former is driven from crankshaft it throughgear train 22, 26 and 24 as described. Dog 48 and abutment or detent 50thus act as a one-way positive drive ratchet clutch mechanism, and areand remain in positive engagement when the two crankshafts aresynchronized, with power being delivered by both.

In case. the engine is required to drive two coaxial propellers, theadvantages of the invention may be realized in the same manner, exceptthat both sides of the engine are connected to each propeller shaft,through suitable gearing, such as is shown, for example, in copendingapplication Serial No. 579,028, filed February 21, 1945 by William J.Petre, now abandoned. Other changes may be made to suit particularoperating requirements, it being understood that the invention is notlimited to the particular embodiments described herein, but issusceptible of changes in form and detail within the scope of theappended claims.

We claim:

1. In a power plant having at least two output shafts, means forseverally driving said shafts, a driven member, means connecting saidshafts together and to said driven member, and mechanism in saidconnecting means for disconnecting one of said shafts from the other andfrom said driven member and for connecting them together at will, saidmechanism comprising a clutch a device, said synchronizing device beingresponsive to equal torque of said shafts for positively connecting themtogether after engagement of said clutch, and being inoperative upondisengagement of said clutch.

2. In a power plant having at least two output shafts, means forseverally driving said shafts, a driven member, means connecting saidshafts together and to said driven member, mechanism in said connectingmeans for disconnecting one of saidshafts from the other and from saiddriven member and for connecting them together at will, said mechanismcomprising a slip clutch and a positive engagement clutch between saidone shaft and the other shaft, and means for engaging and disengagingsaid slip clutch to permit engagement and disengagement of said positiveengagement clutch.

3. In a power plant having at least two output shafts, means for drivingeach shaft and a driven member, the combination of connections from eachshaft to said driven member and between said shafts, said connectionsincluding a pinion on each shaft, a first slip clutch between one ofsaid shafts and its said pinion, a second positive engagement clutchbetween said one shaft and its said pinion, means for engaging anddisengaging said first clutch, and means in said second clutchresponsive to centrifugal force of rotation of said one shaft forrendering said second clutch effective to posiin'vely connect saidshafts after engagement of said first clutch.

4. In a power plant having at least two output shafts and means fordriving each shaft independentiy of the other and in the oppositedirection, the combination of a pinion on one shaft, a pinion on theother shaft but normally disconnected therefrom, a gearing interposedbetween said shaft pinions, a driven member connected to said gearing, aslip clutch interposed between said other shaft and its pinion forconnecting said other shaft to said one shaft for drive thereby, meansfor energizing the driving means of said other shaft driven by said oneshaft to cause said other shaft to operate independently of said oneshaft, and a ratchet clutch interposed between said other shaft and itspinion and rendered effective by said slip clutch to positively connectsaid other shaft to said one shaft through said gearing when said othershaft attains the torque of said one shaft, slippage of said slip clutchaffording relative movement between the elements of said ratchet clutchuntil they engage.

5. In a power plant having at least two output shafts and power meansfor driving each shaft independently of the other, the combination of apinion on one shaft, a pinion on the other shaft but normallydisconnected therefrom, gearing interposed between said shaft pinions,driven members connected to said gearing, a slip clutch interposedbetween said other shaft and its pinion for connecting said other shaftto said one shaft for drive thereby, means for energizing the powermeans of said other shaft driven by said one shaft to cause said othershaft to operate independently of said one shaft, and a ratchet clutchinterposed between said other shaft and its pinion and renderedeffective by said slip clutch to positively connect said other shaft tosaid one shaft through said gearing when said other shaft exceeds theslippage torque of said slip clutch, slippage of said slip. clutchaffording relative movement between the elements of said ratchet clutchuntil they engage.

6. A clutch and synchronizing device for connecting one shaft driven bya first power unit to another shaft driven by another power unit insynchronism and to a driven member driven from said second named shaft,comprising means including a slip clutch connecting said one shaft andsaid other shaft and said driven member for driving said one shaft fromsaid second shaft and permitting relative movement between said shafts,and a one-way positive clutch for drivingly connecting said one shaft tosaid other shaft and to said driven member when said first power unittends to drive said one shaft at higher speed than said other shaft.

CHESTER C. DE PEW.

ALFRED T. GREGORY.

No references cited.

